U.S. patent application number 11/342476 was filed with the patent office on 2006-11-09 for flowing electrolyte battery with electric potential neutralization.
Invention is credited to Gary Colello, Dennis Darcy.
Application Number | 20060251957 11/342476 |
Document ID | / |
Family ID | 36617293 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060251957 |
Kind Code |
A1 |
Darcy; Dennis ; et
al. |
November 9, 2006 |
Flowing electrolyte battery with electric potential
neutralization
Abstract
Flowing electrolyte batteries capable of being selectively
neutralized chemically; processes of selectively neutralizing
flowing electrolyte batteries chemically; and processes of
selectively restoring the electrical potential of flowing
electrolyte batteries are disclosed herein.
Inventors: |
Darcy; Dennis; (Tyugsboro,
MA) ; Colello; Gary; (North Andover, MA) |
Correspondence
Address: |
LATHROP & GAGE LC
4845 PEARL EAST CIRCLE
SUITE 300
BOULDER
CO
80301
US
|
Family ID: |
36617293 |
Appl. No.: |
11/342476 |
Filed: |
January 30, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60648156 |
Jan 28, 2005 |
|
|
|
Current U.S.
Class: |
429/70 ; 429/101;
429/51; 429/81 |
Current CPC
Class: |
H01M 8/04276 20130101;
H01M 10/4214 20130101; Y02E 60/50 20130101; H01M 8/188 20130101;
H01M 8/04238 20130101; Y02E 60/10 20130101; H01M 8/20 20130101;
H01M 12/085 20130101 |
Class at
Publication: |
429/070 ;
429/101; 429/081; 429/051 |
International
Class: |
H01M 2/40 20060101
H01M002/40; H01M 8/20 20060101 H01M008/20; H01M 2/38 20060101
H01M002/38 |
Claims
1. A flowing electrolyte battery, comprising: first and second
electrodes separated by a membrane; and one or more valves
permitting flow of catholyte through the second electrode and
anolyte through the first electrode such that the battery has
electrical potential, or alternatively permitting flow of anolyte
through both first and second electrodes such that the battery is
chemically neutralized.
2. The battery of claim 1, further comprising a first pump in fluid
communication with the valves to force catholyte from a catholyte
reservoir to the second electrode.
3. The battery of claim 1, further comprising a second pump in
fluid communication with the valves to force anolyte from an
anolyte reservoir to the first or second electrode.
4. The battery of claim 1, further comprising: an anolyte reservoir
in communication with a first pump for housing the anolyte and
supplying the first pump with the anolyte; a catholyte reservoir in
communication with a second pump for housing the catholyte and
supplying the second pump with the catholyte; and piping for
connecting the first electrode to the anolyte reservoir such that
the anolyte flows from the first electrode to the anolyte
reservoir, connecting the second electrode to the catholyte
reservoir such that the catholyte flows from the second electrode
to the catholyte reservoir, and connecting the second electrode to
the anolyte reservoir such that anolyte that has flowed through the
second electrode continues to flow to the anolyte reservoir.
5. The battery of claim 4, wherein a first one of the valves is
positioned and configured such that catholyte flows through the
second electrode and enters the catholyte reservoir and such that
anolyte alternately flows through the second electrode to enter the
anolyte reservoir.
6. The battery of claim 5, further comprising a third pump in fluid
communication with the anolyte reservoir, the first electrode, and
the second electrode, for flowing the anolyte through the first and
second electrodes in a direction opposite to a direction of flow
caused by the first and second pumps.
7. The battery of claim 5, further comprising a fourth pump in
fluid communication with the anolyte reservoir and the second
electrode, for flowing the anolyte through the second electrode in
a direction that is the same as a direction of flow caused by the
second pump.
8. The battery of claim 1, wherein at least one of the valves
comprise: a controller in data communication with an interface
conditioner; and first and second actuators in data communication
with the interface conditioner, the first actuator controlling said
one valve for selectively allowing the anolyte to reach the second
electrode, the second actuator controlling a second valve for
selectively allowing the catholyte to reach the second
electrode.
9. The battery of claim 8, wherein the interface conditioner
communicates with the first and second actuators by supplying the
first and second actuators with an electrical signal.
10. The battery of claim 1, further comprising one or more sensors
for detecting an abnormal condition, the valves responding to the
abnormal condition to flow only anolyte through the first and
second electrodes.
11. The battery of claim 1, further comprising a user-activated
switch, the valves responding to the switch to either (a) flow only
anolyte through the first and second electrodes, in a neutralized
mode of operation, or (b) flow anolyte through the first electrode
and catholyte through the second electrode, in a normal mode of
operation.
12. A flowing electrolyte battery having an electric potential that
is selectively neutralized chemically, the battery comprising:
first and second electrodes separated by a membrane; an anolyte
reservoir for housing anolyte; a first pump for selectively forcing
the anolyte from the anolyte reservoir through the first electrode;
a catholyte reservoir for housing catholyte; a second pump for
selectively forcing the catholyte from the catholyte reservoir
through the second electrode; and means for selectively flowing
only anolyte from the anolyte reservoir through the second
electrode.
13. The battery as in claim 12, wherein said means for selectively
flowing comprises a third pump.
14. The battery as in claim 12, wherein said means for selectively
flowing comprises: the first pump; and piping connecting the
anolyte reservoir to the first pump and the first pump to the
second electrode.
15. The battery as in claim 12, further comprising piping
connecting: the anolyte reservoir to the first pump; the first pump
to the first electrode; the first electrode to the anolyte
reservoir; the catholyte reservoir to the second pump; the second
pump to the second electrode; the second electrode to the catholyte
reservoir; the acolyte reservoir to a third pump; and the third
pump to the second electrode.
16. The battery of claim 15, further comprising a first check valve
in communication with the piping that connects the third pump to
the second electrode to selectively restrict anolyte from entering
the second electrode.
17. The battery of claim 16, further comprising a second check
valve in communication with the piping that connects the second
pump to the second electrode to selectively restrict catholyte from
entering the second electrode.
18. The battery of claim 12, further comprising an overflow
connector between the anolyte reservoir and the catholyte
reservoir.
19. A process of selectively neutralizing a flowing electrolyte
battery chemically, comprising: flowing anolyte and catholyte
through electrodes of the electrolyte battery to produce
electricity; determining a neutralization event; and flowing only
anolyte through the electrodes to neutralize the battery's electric
potential.
20. A process of selectively restoring electrical potential of a
flowing electrolyte battery, comprising: determining whether the
battery should have electrical potential; inhibiting flow of
anolyte through one of the battery's electrodes; and flowing
anolyte and catholyte through the battery to produce the electrical
potential.
21. A flowing electrolyte battery, comprising: first and second
electrodes separated by a membrane; and one or more valves
permitting flow of catholyte through the second electrode and
anolyte through the first electrode such that the battery has
electrical potential, or alternatively permitting flow of anolyte
through the first electrode and an electrically neutral fluid
through the second electrode such that the battery is chemically
neutralized.
22. A flowing electrolyte battery, comprising: first and second
electrodes separated by a membrane; an anolyte reservoir in
communication with a first pump for housing the anolyte and
supplying the first pump with the anolyte; a catholyte reservoir in
communication with a second pump for housing the catholyte and
supplying the second pump with the catholyte; piping for connecting
the anolyte reservoir to the first electrode such that the anolyte
flows from the anolyte reservoir to the first electrode, connecting
the first electrode to the anolyte reservoir such that the anolyte
flows from the first electrode to the anolyte reservoir, connecting
the catholyte reservoir to the second electrode such that the
catholyte flows from the catholyte reservoir to the second
electrode, connecting the second electrode to the catholyte
reservoir such that the catholyte flows from the second electrode
to the catholyte reservoir; and means for selectively flowing the
catholyte from the second electrode back to the second electrode
without first entering the catholyte reservoir.
23. The battery of claim 22, wherein said means for selectively
flowing comprises a valve.
24. A process of selectively neutralizing a flowing electrolyte
battery chemically, comprising: flowing anolyte and catholyte
through electrodes of the electrolyte battery to produce
electricity; determining a neutralization event; and flowing only
anolyte and electrically neutral fluid through the electrodes to
neutralize the battery's electric potential.
25. A process of selectively restoring electrical potential of a
flowing electrolyte battery, comprising: determining whether the
battery should have electrical potential; inhibiting flow of
electrically neutral fluid through one of the battery's electrodes;
and flowing anolyte and catholyte through the battery to produce
the electrical potential.
Description
RELATED APPLICATIONS
[0001] The present application claims benefit of priority to
provisional U.S. Patent Application No. 60/648,156, filed Jan. 28,
2005 and titled "Methods and Apparatus for Electric Potential
Neutralization in a Flowing Electrolyte Battery", which is
incorporated herein by reference.
BACKGROUND
[0002] Batteries are used for a wide variety of industrial
applications. For example, buildings containing lead acid batteries
are placed throughout our countryside and within our urban areas
for electrical energy storage, and these batteries are used to keep
telephones, cable TV, and Internet data centers functional when
power is otherwise lost. The most widely used batteries for
industrial applications are the classic lead acid battery, which
are available as flooded cell or valve regulated. Each of these
batteries uses the same basic chemistry; plates of lead and lead
oxide are contained in an electrolyte of sulfuric acid. Battery
terminals are connected to these plates immersed in
electrolyte.
[0003] Flowing electrolyte batteries have two electrolytes, anolyte
and catholyte, that are circulating and separated by a membrane. In
the case of zinc bromine flowing electrolyte battery, zinc is
plated out during charge and consequently frees up bromide ions
that diffuse across the membrane. In this case, the anolyte becomes
increasingly zinc depleted and the catholyte becomes increasingly
bromine rich. An electrical potential develops across this membrane
due to the presence of metal on one side of the membrane, such as
zinc, and a catholyte on the other side of the membrane. The
catholyte is rich in cation concentration such as bromide.
[0004] In the event of a fire within a facility containing
industrial batteries, or in the event of a battery malfunction, the
batteries may become unsafe and the energy that they store may
become readily available to the outside world. Fire departments
proceed with great caution into fires in such facilities because of
the danger of electrical shock or explosion that may occur in the
event of a battery failure. Previously, there has not been a way to
turn batteries off chemically.
[0005] Also, in the event of non-use, a battery can self discharge
due to reactant available in the reaction cell. The reactant causes
a slow diffusion through the membrane to slowly discharge the
battery. Previously, there has not been a way to neutralize
batteries chemically to stop this self discharge in times of
non-use.
SUMMARY
[0006] A battery in which electric potential is quickly neutralized
chemically would increase safety in situations such as those
described above and prevent self discharge in times of non-use.
Accordingly, flowing electrolyte batteries capable of being
selectively neutralized chemically and processes of selectively
neutralizing a flowing electrolyte battery chemically are disclosed
herein. A battery of one embodiment includes first and second
electrodes separated by a membrane. One or more valves permit (1)
flow of catholyte through the second electrode and anolyte through
the first electrode such that the battery has electrical potential,
or alternately (2) flow of anolyte through both first and second
electrodes such that the battery is chemically neutralized.
[0007] In an embodiment, a flowing electrolyte battery having an
electric potential that is selectively neutralized chemically is
provided. The battery includes first and second electrodes
separated by a membrane, an anolyte reservoir for housing an
anolyte, and a catholyte reservoir for housing a catholyte. A first
pump selectively forces the anolyte from the anolyte reservoir
through the first electrode, and a second pump selectively forces
the catholyte from the catholyte reservoir through the second
electrode. Means are included for selectively forcing only anolyte
from the anolyte reservoir through the second electrode.
[0008] In an embodiment, a process of selectively neutralizing a
flowing electrolyte battery chemically is provided. The method
includes the steps of (1) flowing anolyte and catholyte through
electrodes of the electrolyte battery to produce electricity; (2)
determining a neutralization event; and (3) flowing only anolyte
through the electrodes to neutralize the battery's electric
potential.
[0009] In an embodiment, a process of selectively restoring
electrical potential of a flowing electrolyte battery is provided.
The method includes the steps of (1) determining whether the
battery should have electrical potential; (2) inhibiting flow of
anolyte through one of the battery's electrodes; and (3) flowing
anolyte and catholyte through the battery to produce electric
potential.
[0010] In an embodiment, a flowing electrolyte battery having an
electric potential that is selectively neutralized chemically is
provided. The battery includes first and second electrodes
separated by a membrane. One or more valves permit (1) flow of
catholyte through the second electrode and anolyte through the
first electrode such that the battery has electrical potential, or
alternately (2) flow of anolyte through both the first electrode
and an electrically neutral fluid through the second electrode such
that the battery is chemically neutralized.
[0011] In an embodiment, a flowing electrolyte battery having an
electric potential that is selectively neutralized chemically is
provided. The battery includes first and second electrodes
separated by a membrane, an anolyte reservoir in communication with
a first pump for housing anolyte and supplying the first pump with
the anolyte, and a catholyte reservoir for housing catholyte and
supplying the second pump with the catholyte. Piping is included
for: connecting the anolyte reservoir to the first electrode such
that the anolyte flows from the anolyte reservoir to the first
electrode; connecting the first electrode to the anolyte reservoir
such that the anolyte flows from the first electrode to the anolyte
reservoir; connecting the catholyte reservoir to the second
electrode such that the catholyte flows from the catholyte
reservoir to the second electrode; and connecting the second
electrode to the catholyte reservoir such that the catholyte flows
from the second electrode to the catholyte reservoir. Means are
included for selectively flowing the catholyte from the second
electrode back to the second electrode without first entering the
catholyte reservoir.
[0012] In an embodiment, a process of selectively neutralizing a
flowing electrolyte battery chemically is provided. The method
includes the steps of (1) flowing anolyte and catholyte through
electrodes of the electrolyte battery to produce electricity; (2)
determining a neutralization event; and (3) flowing only anolyte
and electrically neutral fluid through the electrodes to neutralize
the battery's electric potential.
[0013] In an embodiment, a process of selectively restoring
electrical potential of a flowing electrolyte battery is provided.
The method includes the steps of (1) determining whether the
battery should have electrical potential; (2) inhibiting flow of
electrically neutral fluid through one of the battery's electrodes;
and (3) flowing anolyte and catholyte through the battery to
produce electric potential.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 schematically shows a prior art flowing electrolyte
battery.
[0015] FIG. 2 schematically shows one flowing electrolyte battery
with electric potential neutralization.
[0016] FIG. 3 schematically shows another flowing electrolyte
battery with electric potential neutralization.
[0017] FIG. 4 schematically shows a valve according to an
embodiment.
[0018] FIG. 5 schematically shows another flowing electrolyte
battery with electric potential neutralization.
[0019] FIG. 6 schematically shows another flowing electrolyte
battery with electric potential neutralization.
[0020] FIG. 7 is a flowchart illustrating a process of selectively
neutralizing a flowing electrolyte battery chemically and
subsequently restoring electric potential.
[0021] FIG. 8 schematically shows another flowing electrolyte
battery with electric potential neutralization.
[0022] FIG. 9 schematically shows another flowing electrolyte
battery with electric potential neutralization.
[0023] FIG. 10 is a flowchart illustrating another process of
selectively neutralizing a flowing electrolyte battery chemically
and subsequently restoring electric potential.
[0024] FIGS. 11-15 show example test results for one flowing
electrolyte battery with electric potential neutralization
DETAILED DESCRIPTION
[0025] FIG. 1 shows a typical configuration for a flowing
electrolyte battery 100. Battery 100 includes bipolar carbon
electrodes 101 separated by a membrane 108 that is porous to
cations, a catholyte tank 102, and an anolyte tank 103. A pump 104
circulates anolyte and a separate pump 107 circulates catholyte. A
secondary catholyte 105 may also be included, which in the case of
a zinc bromide flowing electrolyte battery 100 is a polybromide
complex. A valve 106, e.g., a polybromide complex valve, allows
pump 107 to pull polybromide complex 105 from a bottom of a tank
during battery electrical discharge. Battery 100 provides potential
energy across membrane 108 when catholyte and anolyte pass through
electrodes 101 on respective sides of membrane 108.
[0026] FIG. 2 shows a flowing electrolyte battery 200(1) capable of
being turned off chemically, to provide electric potential
neutralization. Battery 200(1) may be a zinc bromine flowing
electrolyte battery or another flow-type battery. An anolyte
electrolyte reservoir 201 is in fluid communication with an anolyte
pump 205, and a catholyte reservoir 202 is in fluid communication
with a catholyte pump 206. With pump 205 operating, anolyte flows
through a carbon electrode 203, which is separated from a catholyte
electrode 204 by a membrane 209. With pump 206 operating, anolyte
or catholyte flows through catholyte electrode 204, as now
described. Piping 210 is appropriately arranged to connect the
various elements, such as shown in FIG. 2, for example. Two valves
208, 207 are positioned to direct flow of catholyte or anolyte
through catholyte electrode 204.
[0027] In normal operation, valve 208 only allows catholyte from
catholyte reservoir 202 through catholyte electrode 204, and valve
207 only allows electrolyte passing through catholyte electrode 204
to enter catholyte reservoir 202. In a neutralized mode, however,
valve 208 only allows anolyte from anolyte reservoir 201 through
catholyte electrode 204, and valve 207 only allows electrolyte
passing through catholyte electrode 204 to enter anolyte reservoir
201. Battery 200(1) is thus neutralized ("turned off") chemically
when in the neutralized mode. Valves 207 and 208 are shown in the
neutralized mode in FIG. 2. Valves 207 and 208 may be made up of
individual valves connected together to act in concert; valves 207
and 208 may be check valves or another type of valve.
[0028] Provided that there is no break in piping 210 and pumps 205,
206 are functional, the electric potential of battery 200(1)
returns when valves 207 and 208 are returned to the normal position
(i.e., so that catholyte flows through electrode 204). In other
words, the electrical potential of battery 200(1) may be brought to
zero without removing the charge, and original electric potential
may be restored with no appreciable loss of stored energy. This is
notable because a battery is typically charged to a voltage and can
only return to zero volts by fully discharging the battery's
electric potential.
[0029] FIG. 3 shows a flowing electrolyte battery with electric
potential neutralization 200(2) which includes an additional pump
300 and additional valves 301, 302 in parallel. Additional pump 300
may be used to drive electrolyte in a reverse direction (i.e., in a
direction opposite arrows 205a, 206a shown in FIG. 3) through
battery 200(2) in the event of a failure in a supply side 210a of
piping 210. Normally, electrolyte may be pumped through pumps 205,
206 in the direction of arrows 205a, 206a, respectfully. In the
event battery 200(2) is put into a neutralized mode, however,
valves 207, 208 are configured such that anolyte (e.g., a zinc
depleted electrolyte) may be pumped through both electrode 203 and
electrode 204 and returned to anolyte reservoir 201 as described
above.
[0030] Normally, valve 301 may be closed, and valve 302 may be open
to allow anolyte to flow from electrode 203 (and sometimes from
electrode 204 as described above) to anolyte reservoir 201. If pump
300 is an impeller driven pump rather than a positive displacement
pump, valves 301, 302 may not be used because such a pump 300
allows anolyte to flow through pump 300 to anolyte reservoir
201.
[0031] If piping 210a supplying electrolyte from pump 205, pump
205, or another relevant element fails, making it difficult to
displace the fluid in the catholyte side 204 of battery 200(2),
pump 300 may be activated. Upon activation of pump 300, valve 401
may be opened to allow anolyte to flow from anolyte reservoir 201,
valve 302 may be closed to prevent electrolyte from flowing around
pump 300, and valves 207 and 208 may be configured to allow anolyte
from anolyte reservoir 201 to flow through electrode 204. As a
result, electrolyte may flow backwards (i.e., in a way opposite the
arrows shown in FIG. 3) through battery 200(2).
[0032] FIG. 4 shows an exemplary embodiment of valve 208. In this
embodiment, valve 208 includes a controller 401, an interface
conditioner 402, a power supply 403, first and second valves 404,
404a, and first and second valve actuators 406, 406a. Controller
401 may be, for example, a programmable logic array, a
microcontroller or microprocessor, a switch, or a comparator having
logic to look for an abnormal data signal (e.g., an abnormal
pressure, voltage, or temperature data signal, or another signal
indicating the presence of a leak); this abnormal data signal may
thus trigger a neutralization event such as described hereinbelow.
Controller 401 may be in data communication with a switch 411, a
pressure sensor 412, a voltmeter 413, a thermometer 414, and/or a
leak detector 415.
[0033] Interface conditioner 402 places controller 401 in data
communication with first and second valve actuators 406, 406a, such
as by supplying first and second valve actuators 406, 406a with
appropriate voltage or current levels. Actuators 406, 406a
communicate with valves 404, 404a, respectfully, to position valves
404, 404a in open or closed conditions in accordance with signals
(e.g., particular voltages or currents) received from interface
conditioner 402. Valves 404, 404a may be ball valves or valves of
another type, and when one valve 404, 404a is open, the other valve
404, 404a is closed. Power supply 403 may supply power to any or
all of controller 401, interface conditioner 402, first valve
actuator 406, and second valve actuator 406a, for example.
[0034] Valves 404, 404a and actuators 406, 406a may be standard
piping parts capable of being purchased out of a catalog. An
exemplary actuator 406, 406a is Asahi America Series 83 Actuator
Electromni, and an exemplary valve 404, 404a is a Type 21 ball
valve. Valves 404, 404a may include a non-reactive plastic such as
PVDF in the case bromine zinc reactants are used.
[0035] In an exemplary method of use, controller 401 sends first
and second valve actuators 406, 406a a "normal" signal via
interface conditioner 402 to cause valve 404a to be at an open
configuration and valve 404 to be at a closed configuration. This
allows the corresponding battery (e.g., battery 200(1), battery
200(2)) to function in a normal mode of operation; catholyte from
catholyte reservoir 202 and pipe 408a thus flows through pipe 409
to electrode 204. When controller 401 detects a neutralization
event (e.g., switch 411 being turned off, abnormal pressure,
voltage, temperature, or another indication of a leak), controller
401 sends a "neutralize" signal via interface conditioner 402 to
cause valve 404a to be at a closed configuration and valve 404 to
be at an open configuration. This allows battery 200(1), 200(2) to
be turned off chemically as discussed above; anolyte from anolyte
reservoir 201 and pipe 408 thus flows out of pipe 409 to electrode
204. If controller 401 later sends another "normal" signal to cause
valve 404a to be at the open configuration and valve 404 to be at
the closed configuration, the electric potential of the battery is
restored; that is, catholyte from catholyte reservoir 202 and pipe
408a again flows through pipe 409 to electrode 204.
[0036] Switch 411 may be turned off, for example, to prevent self
discharge of battery 200(1), 200(2) in times of non-use. When
battery 200(1), 200(2) is neutralized as discussed above, this self
discharge is stopped because the reactants are removed and stored
safely away from the reaction site. However, if switch 411 is
turned off for this reason, the time required for restoring the
electric potential of battery 200(1), 200(2) may be unacceptable if
battery 200(1), 200(2) is being used as an uninterruptible
(back-up) power supply. In this case, it may be desirable to
neutralize only some batteries 200(1), 200(2) and maintain the
electric potential of other batteries 200(1), 200(2) so that the
available electric potential is able to temporarily carry the
required load and power pumps 205, 206 to restore the electric
potential of neutralized batteries 200(1), 200(2).
[0037] FIG. 5 shows an embodiment of a flowing electrolyte battery
with electric potential neutralization 200(3); battery 200(3)
includes a pump 510 and first and second check valves 511, 512 to
selectively supply electrolyte from anolyte reservoir 201 to
electrode 204. Pump 510 is sized such that, when turned on, it
forces check valve 511 open and check valve 512 closed. As shown,
pump 510 only pumps electrolyte from anolyte reservoir 201 in
direction 510a to electrode 204, and check valves 511, 512 only
permit fluid flow in one direction.
[0038] In an exemplary method of use, pump 510 is turned off under
normal conditions. When pump 510 is turned off, pressure from pump
206 forces fluid through valve 512 and forces valve 511 closed.
However, if pump 510 is energized, anolyte from anolyte reservoir
201 is forced through valve 511 and electrode 204, and valve 512 is
forced closed. The electrical potential of battery 200(3) is thus
brought to zero without removing the charge.
[0039] As shown in FIG. 5, electrolyte from electrode 204 may enter
catholyte reservoir 202 regardless of whether the electrolyte is
acolyte or catholyte. Since this will be done for only a short
period of time, there will be (at most) only a small amount of
anolyte delivered to catholyte reservoir 202. However, an overflow
connector (not shown) may be included between the anolyte and
catholyte reservoirs 201, 202 to prevent a respective reservoir
from becoming over-full. The bromide rich electrolyte will thus
sink to the bottom of the reservoir, and the top layer will be
compatible with the anolyte. Therefore, overflow from the top of
the reservoir will not force the bromide rich electrolyte into
anolyte reservoir 201.
[0040] FIG. 6 shows an embodiment of a flowing electrolyte battery
with electric potential neutralization 200(4) that may function
substantially as described above in reference to FIG. 5, though
without check valve 512. Although not shown, the embodiment
described in FIG. 5 may also function without check valve 511 and
check valve 512. In removing valve 511 and/or valve 512, piping and
pumps 206, 510 may be configured and sized such that there is no
cross-flow; catholyte from reservoir 202 may be selectively forced
through electrode 204; and anolyte from reservoir 201 may be
selectively forced through electrode 204.
[0041] FIG. 7 shows a process 700 of selectively neutralizing a
flowing electrolyte battery chemically and subsequently restoring
its electric potential. In step 701, anolyte and catholyte are
flowed through an electrolyte battery to produce electricity. In an
example of step 701, pumps 205, 206 pump anolyte and catholyte
through electrodes 203, 204, as shown in FIG. 2. In step 702, a
neutralization condition is determined. In an example of step 702,
as discussed in reference to FIG. 4, controller 401 detects an
event (e.g., switch 411 is turned off by a user) and/or an abnormal
condition (e.g., an abnormal pressure detected by pressure sensor
412; an abnormal voltage detected by voltmeter 413; an abnormal
temperature detected by thermometer 414; and/or an indication of a
leak by leak detector 415).
[0042] In step 703, only anolyte is flowed through the battery to
neutralize the battery's electric potential. In an example of step
703, valves 207, 208 and pump 205 cooperate to introduce only
anolyte through electrodes 203, 204, as shown in FIG. 2. If valve
208 is substantially as described in reference to FIG. 4,
controller 401 sends a "neutralize" signal via interface
conditioner 402 to cause valve 404a to be at a closed configuration
and valve 404 to be at an open configuration. Additional examples
are discussed above in reference to FIGS. 5 and 6, such as where
pump 510 flows anolyte through electrodes 203, 204.
[0043] In step 704, a resume normal operation condition is
determined in which electric potential is desired. In an example of
step 704, controller 401 detects an event (e.g., switch 411 is
turned on by a user) and/or a normalized condition is detected
(e.g., a normal pressure detected by pressure sensor 412; a normal
voltage detected by voltmeter 413; a normal temperature detected by
thermometer 414; or another indication of normal conditions).
[0044] FIG. 8 shows an embodiment of a flowing electrolyte battery
with electric potential neutralization 200(5) that includes a
neutral fluid reservoir 801 in fluid communication with a pump 805
and valves 207, 208. An electrically neutral fluid (e.g., an
electrolyte with reactant removed) may be contained in neutral
fluid reservoir 801. In the case of a zinc bromine flowing
electrolyte battery, an example of an electrically neutral fluid is
electrolyte with bromine removed.
[0045] In normal operation, valve 208 only allows catholyte from
catholyte reservoir 202 through catholyte electrode 204, and valve
207 only allows electrolyte passing through catholyte electrode 204
to enter catholyte reservoir 202. In a neutralized mode, however,
valve 208 only allows neutral fluid from neutral fluid reservoir
801 through catholyte electrode 204, and valve 207 only allows
electrolyte passing through catholyte electrode 204 to enter
neutral fluid reservoir 801. Battery 200(5) is thus neutralized
("turned off") chemically when in the neutralized mode. Valves 207
and 208 are shown in the neutralized mode in FIG. 8.
[0046] Provided that there is no break in piping 210 and pumps 205,
206 are functional, the electric potential of battery 200(5)
returns when valves 207 and 208 are returned to the normal position
(i.e., so that catholyte flows through electrode 204). In other
words, the electrical potential of battery 200(5) may be brought to
zero without removing the charge, and original electric potential
may be restored with no appreciable loss of stored energy.
[0047] FIG. 9 shows an embodiment of a flowing electrolyte battery
with electric potential neutralization 200(6) that includes a valve
901 that selectively allows electrolyte flowing out of electrode
204 to re-enter electrode 204 without first returning to catholyte
reservoir 202. This allows reactants in the electrolyte to be used
up (or to become "electrically neutral") with no appreciable loss
of energy, since the reactants are not replenished. In this way,
electrode 204 and battery 200(6) become electrically neutral in a
short period of time without an appreciable loss of stored
energy.
[0048] FIG. 10 shows a process 1000 of selectively neutralizing a
flowing electrolyte battery chemically and subsequently restoring
its electric potential. In step 1001, anolyte and catholyte are
flowed through an electrolyte battery to produce electricity. In an
example of step 1001, pumps 205, 206 pump anolyte and catholyte
through electrodes 203, 204, as shown in FIG. 8. In step 1002, a
neutralization condition is determined. In an example of step 1002,
as discussed in reference to FIG. 4, controller 401 detects an
event (e.g., switch 411 is turned off by a user) and/or an abnormal
condition (e.g., an abnormal pressure detected by pressure sensor
412; an abnormal voltage detected by voltmeter 413; an abnormal
temperature detected by thermometer 414; and/or an indication of a
leak by leak detector 415).
[0049] In step 1003, only anolyte and an electrically neutral fluid
is flowed through the battery to neutralize the battery's electric
potential. In an example of step 1003, valves 207, 208 and pump 805
cooperate to introduce only electrically neutral fluid through
electrode 204, as shown in FIG. 8. An additional example is
discussed above in reference to FIG. 9, such as where valve 901
causes electrolyte flowing out of electrode 204 to re-enter
electrode 204 without first returning to catholyte reservoir
202.
[0050] In step 1004, a resume normal operation condition is
determined in which electric potential is desired. In an example of
step 1004, controller 401 detects an event (e.g., switch 411 is
turned on by a user) and/or a normalized condition is detected
(e.g., a normal pressure detected by pressure sensor 412; a normal
voltage detected by voltmeter 413; a normal temperature detected by
thermometer 414; or another indication of normal conditions).
Experimental Results
[0051] Test results from experiments conducted on a battery stack
of batteries 200(1) are shown in FIGS. 11 through 15. ZincFlow 45
software was used to control the DC power into and out of the stack
except for a brief period during the recovery after float. The test
stack was charged for about 41/2 hr at 13.5 Amps. It was then
flushed out with anolyte and floated without rinse cycles for 19
hours. Next, varying loads from a resistor load bank were applied
to the stack with pumps 205, 206 off until stack voltage collapsed.
Catholyte and anolyte pumps 205, 206 were then turned on, and
bromine complex was pumped into the cathode half cells 204. After
voltage recovery, ZincFlow 45 software was used to strip the stack.
The graphs of FIGS. 11 and 12 show complete cycle data.
[0052] FIG. 13 shows the time period where the charging of the
stack is stopped and anolyte is flushed through the cathode half
cells 204. The stack flushing procedure was 1) turn off catholyte
pump 206; 2) close valves 207, 208 to isolate catholyte reservoir
202 and pump 206; and 3) open valves 207, 208 to allow anolyte to
circulate through the cathode half cells 204 and back to anolyte
reservoir 201. This procedure introduced enough bromine complex
into anolyte reservoir 201 to color up the anolyte. In retrospect,
closing off the return line to catholyte reservoir 202 should be
delayed for a few seconds until the anolyte is seen coming out of
cathode half cells 204. Anolyte was flushed through the stack for
90 seconds, and anolyte pump 205 was then turned off. After a 5
minute rest, this process was repeated until the discharged
electrolyte from both cathode and anode half cells 203, 204 was a
uniform color. A total of 3.times.90 seconds was needed.
[0053] FIG. 14 details the stack OCV during float.
[0054] FIG. 15 details the stack's recovery after float. At the end
of the float time, loads from a resistor bank were applied to the
stack with pumps 205, 206 remaining off to determine the residual
power and energy in the stack. Because there was no replacement of
bromine consumed on the cathodes 204, the stack voltage collapsed
very quickly to less than 40 volts. After the load was removed,
stack voltage recovered to approximately 70 volts. With pumps 205,
206 still off, the load was reapplied to the stack, and then
catholyte and anolyte electrolyte pumps 206, 205 were turned on
with the complex valve opened. It took about one minute from the
time pumps 205, 206 were turned on for bromine complex to reach the
cathode half cells 204. An additional three minutes was needed for
recovery of stack voltage. The resistor load was then removed, and
the stack reconnected to the DC/DC for stripping by the ZincFlow 45
program. The software orders constant power discharge at
approximately 1.3 kW to less than 53 volts. The software then
switches over to constant voltage discharge to 4 Amps. Both voltage
and current are then allowed to decay.
[0055] Those skilled in the art appreciate that variations from the
specified embodiments disclosed above are contemplated herein and
that the described test results are not limiting. The description
should not be restricted to the above embodiments or test results,
but should be measured by the following claims.
* * * * *